UVs on Blender and Substance Painter are different
If you want to export your model to other softwares (like substance painter), you have to apply your modifier first.

When applied, you can see that your UV are broken, you have to re-unwrap.



Little tips after seeing your .blend : when you used mirror modifier, be sure to have all your half-mesh on the same side. This will prevent arrival of weird artefacts or bugs.